Well my due date is august 13 and my last period was nov.20
There's a calendar that works it out for you if you google it. Can't remember the name but just google due date calendar or conception calendar.
My last period was nov 3 & I'm due August 10
My due date is also August 14th. The last period was November 7th and I conceived november 21st.
On this app if you go to your home page, you can put in your expected due date. It will show it on a time line of your conceived date & how close you are to the expected arrival date(: Hope this helped!